The present disclosure relates to a medical apparatus. In particular, the present disclosure relates to a medical apparatus and method adapted for converting medical signals for use in maternal and fetal monitoring.

Medical devices are widely used for measuring a wide variety of monitoring signals. Monitoring signals, or raw signals received from the patient by the medical device, typically contain specific bioinformation or data of interest to a clinician. Common medical signals include electrocardiogram (ECG) signals or fetal and maternal signals, such as for example, uterine temperature, intrauterine pressure, electric fetal electrocardiogram signals, etc. Such signals from the patient are gathered by various sensors and transmitted via electrical cables to a monitor. The monitor displays or records the selected bioinformation contained in the monitoring signal.

Unfortunately, some of the various sensors employed (e.g., electrode, electrode arrays, temperature sensors, pressure transducers, catheters, etc.) to gather the bioinformation are often incompatible with the monitor available to the clinician. For example, the monitor may be compatible with a single medical device, or family of medical devices, or configured to receive signals with specific electrical characteristics (i.e. 4-20 mA, 0-5 VDC, 0-200 mV, etc...). Other causes of incompatibility include inconsistencies in the hardware used with the various monitors and/or development of new sensor or medical equipment not adapted for use with existing monitors.

The aforedescribed incompatibility between the various sensors and an existing monitor, regardless of the reason, causes several problems. Clinicians may be required to stock several different monitors and/or sensors for use with a specific monitor, therefore increasing the cost of medical care. Physical replacement of a monitor sensor may increase the duration of time of the medical procedure. Finally, the cost of introducing newly developed sensors may be prohibitive in that such sensors may require the purchase of new monitors compatible with the newly developed sensors. Therefore, there exists a need for an apparatus that substantially eliminates or minimizes incompatibilities between a medical sensor and a monitor.

In accordance with the present disclosure, an apparatus for replicating a medical signal includes an input adapted to receive at least one medical signal transmitted via a first medical device coupled to the body of a patient, signal processing circuitry adapted to generate at least one replicated signal from the at least one medical signal, and an output. The at least one replicated signal is indicative of being transmitted via a second medical device different than the first medical device. The output is adapted to deliver the at least one replicated signal to an external device configured to receive signals from the second medical device.

The signal processing circuitry may include an analog to digital converter, a signal processor and a digital to analog converter. The analog to digital converter is adapted to convert the at least one medical signal to a digital format. The signal processor processes the at least one medical signal in a digital format wherein data is extracted from the at least one medical signal. The signal generator receives the data extracted by the signal processor and generates therefrom the at least one replicated signal. The data relayed by the at least one replicated signal replicates data potentially outputted by the second medical device. The digital to analog converter converts the at least one replicated signal to an analog format. Alternatively, the signal processing circuitry comprises an ASIC. The signal processor is adapted to select one signal of the at least one converted output signal for extracting and processing data relayed by the selected signal.

The first medical device may be selected from a group consisting of at least one medical electrode and a medical electrode sensor array. The second medical device may be a tocodynamometer, an intrauterine pressure catheter or an ultrasound transducer. In the alternative, the first and second medical devices may be selected from a group consisting of at least one medical electrode, a medical electrode sensor array, an abdominal strain gage, a tocodynamometer, an intrauterine pressure catheter, and an ultrasound transducer, a vacuum pressure sensor, a fetal pulse oximeter, a pH sensor, a cervical dilation sensor, a cervical effacement sensor, a cervical length sensor and a fetal station sensor.

One or more indicators for indicating functionality of the first medical device may be provided. The one or more indicators may be selected from a group consisting of a visual indicator, an auditory indicator and a tactile indicator. The one or more indicators preferably indicates the quality of the at least one medical signal transmitted via the first medical device.

An electrical cable for relaying the at least one signal to the signal processing circuitry is included. An electrical receptacle is adapted for mating with an end of the electrical cable for performing a diagnostic check on the cable.

The at least one output signal includes data selected from a group consisting of heart, fetal, and uterine activity data. The first medical device may be a fetal monitoring electrode and the at least one signal may be a fetal monitoring signal outputted by the fetal monitoring electrode. The at least one output signal includes a uterine activity signal, and further comprising means for shorting the uterine activity signal to zero.

Other embodiments are also envisioned.

Various embodiments of the present disclosure are described herein with reference to the drawings wherein:

FIG. 1 is a view of a maternal and fetal monitoring system incorporating a signal replication medical apparatus in accordance with the present disclosure;

FIG. 2 is an electrical schematic illustrating the components of the signal replication medical apparatus; and

FIG. 3 is a programming flowchart illustrating functionality of the signal replication medical apparatus.

Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

In the discussion which follows, the term "cable" may incorporate a single conductor or may comprise an assembly of conductors arranged in any mode of operation known in the art. Connector refers to a single plug, receptacle, or other device capable of connecting to a cable, device or apparatus. A connector assembly refers to the connection between two connectors wherein the connectors facilitate connectivity between two cables, devices or apparatus, or any combination thereof. Connection or coupling between the two components may be mechanical, electro-mechanical or solely electrical without any mechanical means of connection. Such electrical coupling or connection may be infrared or incorporate electromagnetic wave principles. Thus, the term "connection" or "electrical connection" is to be construed as any electrical, mechanical connection or combination thereof known in the art.

FIG. 1 illustrates a maternal and fetal monitoring system 10 in conjunction with the signal replication medical apparatus 100 according to the present disclosure. The maternal and fetal monitoring system 10 generally includes an electrode array 20 and a monitor 40. The electrode array 20 may include a plurality of electrodes 21 adapted to adhere to skin on the abdomen A of the patient P. One suitable electrode array in described in a U.S Provisional Application titled Radial Electrode Array, application number 60/798,842 and converted to a U.S. Utility Application, Attorney Docket Number H-KN-00380, (1502-124), concurrently filed on September 29, 2006 with the present application, the entire contents of which are incorporated herein by reference. The electrode array disclosed in this application includes a flexible substrate adapted to generally conform to a topography of a skin surface and having a central portion arranged about a central focal point and a plurality of finger-like projections extending radially outwardly from said central portion, a medical electrode disposed on at least one of the finger-like projections and a connector in electrical communication with the medical electrode and adapted to connect to an electronic system.

Typically, monitoring device 40 is configured to receive a monitoring signal from a specific type of medical device with the monitoring signals having specific electrical characteristics. For example, first input connector 40a of monitoring device 40 is configured to receive a monitoring signal from an intrauterine pressure (IUP) catheter wherein the monitoring signal contains maternal intrauterine pressure medical signals. The electrical characteristics of a monitoring signal from an IUP catheter is typically an alternating current or direct current signal, as driven by the excitation voltage of the monitor to which it is connected, of amplitude less than 1 Volt. The amplitude of the IUP monitoring signal changes in response to changes in intrauterine pressure. Second input connector 40b of monitoring device 40 may be configured to receive a monitoring signal from a fetal scalp electrode wherein the monitoring signal contains a fetal electrocardiogram (FECG) medical signal. The electrical characteristics of a monitoring signal from a fetal scalp electrode is typically an electrical potential of less than 1 Volt which characterizes the periodic polarization and depolarization of the fetal heart muscle.

In the maternal and fetal monitoring system 10 of FIG. 1, several incompatibilities exist between monitoring device 40 and the monitoring signals from electrode array 20. Monitoring device 40 is physically incompatible with electrode array 20 since monitoring device 40 receives only two monitoring signals while electrode array 20 supplies eight monitoring signals. Monitoring device 40 is electrically incompatible with electrode array 20 since the signal characteristics of electrode array 20 are different than the signal characteristic required for the first and second input connectors 40a, 40b. Finally, monitoring device 40 is configured to receive two monitoring signals, with each containing a single predominant medical signal, while electrode array 20 supplies eight monitoring signal, with each monitoring single containing a portion of several medical signals. With an electrode array 20, the uterine electromyogram (EHG) and FECG medical signals must be extracted from the eight monitoring signals as described in U.S. Application 10/857,107 and U.S. Application 11/140,057, both to Marossero et al., the contents of which are incorporated herein by reference. Even if monitoring device 40 could physically and electrically receive monitoring signals from an electrode array 20, monitoring device 40 lacks the processing capability to extract medical signals from the plurality of monitoring signals.

Signal replication medical apparatus 100, as described herein, is used to resolve an incompatibility between any medical device and any monitoring device. Signal replication medical apparatus 100 consists of a housing 102 which houses a plurality of connectors 110, 111, output cables 151A, 151B, indicators I and user interface devices 112, 132, 134 described hereinbelow. Housing 102 may be sufficiently small and manufactured from lightweight materials, such as plastic, such that the signal replication medical apparatus 100 is a light-weight inline device.

Input connector 110 of the signal replication medical apparatus 100 is adapted to connect to a first end 50A of an electrical cable 50. Second end 508 of electrical cable 50 connects to a medical device, such as an electrode array 20. It is envisioned signal replication medical apparatus 100 described herein may have any number of inputs and may connect to any number of medical devices.

First and second output cables 151A, 151B of the signal replication medical apparatus 100 are adapted to connect to an electrical system, such as a monitoring device 40, capable of receiving a monitoring signal. It is envisioned signal replication medical apparatus 100 described herein may have any number of outputs, in the form of output cables or output connectors, and may connect to any number of electrical systems capable of receiving a monitoring signal from a medical device.

Electrodes 21 on electrode array 20 receive monitoring signals from the patient and fetus, including signals from maternal uterine muscle and from the maternal and fetal heart muscles. Monitoring signals from electrodes 21 on electrode array 20 are transmitted through electrical cable 50 to the signal replication medical apparatus 100. In this particular embodiment, electrical cable 50 transmits eight individual monitoring signals, one from each electrode 21 on electrode array 20, to signal replication medical apparatus 100 with each monitoring signal containing at least a portion of several maternal and fetal medical signals.

First and second output cables 151a, 151b of signal replication medical apparatus 100 connect to the first and second input connectors 40a, 40b, respectively, of monitoring device 40. Output signals from the signal replication medical apparatus 100 are transmitted on first and second output cables 51a, 51b to monitoring device 40.

FIG. 2 is an electrical schematic illustrating the components of the signal replication medical apparatus 100 in a maternal and fetal monitoring system 10 including an electrode array 120 positioned on the abdomen A of patient P and a monitoring device 140. Signal replication medical apparatus 100 includes signal processing circuitry 160, operably. coupled to the various input connectors, output cables, test connectors and indicator devices described hereinbelow.

Signal processing circuitry 160 may include an analog to digital (A/D) converter 160A, a digital signal processor (DSP) 160B, a signal generator 160C and a digital to analog (D/A) converter 160D. Signal processing circuitry 160 is adapted to receive at least one monitoring signal from a first medical device, such as an electrode array 120. A/D converter 160A converts the analog monitoring signal from a first medical device to a digital representation of the analog monitoring signal. DSP 160B, having a memory storing a set of programmable instructions capable of being executed by the DSP 160B for performing the functions described herein, processes the converted monitoring signal. Processing may include the extraction of a medical signal from a monitoring signal, extraction of one or more medical signals from a plurality of monitoring signals or determination if the signal is a valid signal. Signal generator 160C receives at least a portion of processed data from DSP 160B and generates replicated data indicative of a monitoring signal outputted by a second medical device. The replicated data is different than the monitoring signal from the first medical device and is compatible with monitoring device 140. D/A converter 160D converts the replicated data generated by the signal generator 160C to an analog signal and analog signal is outputted to an output cable 151A, 151B. Output cable 151A, 151B transmits replicated analog signal to monitoring device 140; and the medical signal is presented on display 141.

Signal processing circuitry 160 may be an application-specific integrated circuit (ASIC) customized for this particular use or may be a general purpose device adapted for this use. The functions performed by the various elements 160A-D of signal processing circuitry 160 may be performed in a variety of ways as known in the art

More specifically, first input connector 140A on monitoring device 140 is configured to receive an IUP catheter monitoring signal containing a maternal intrauterine pressure medical signal. Second input connector 140B is configured to receive a fetal scalp electrode monitoring signal, containing a FECG medical signal. Electrode Array 120 supplies eight monitoring signals to signal processing circuitry 160 with each monitoring signal containing at least a portion of several fetal and maternal medical signals (e.g. FECG medical signal, maternal ECG medical signal and maternal EHG medical signal). Electrode array 120 is therefore incompatible with monitoring device 140.

Signal replication medical apparatus 100 receives the plurality of monitoring signals from electrodes 121 on electrode array 120 through electrical cable 150. The A/D converter 160A converts the monitoring signals, DSP 160B extracts the EHG medical signal and the FECG medical signal from the monitoring signals. Signal generator 160C replicated an EHG monitoring signal and an FECG monitoring signal indicative of a monitoring signal from an IUP catheter and a fetal scalp electrode, respectively. A/D converter 160D converts the replicated IUP and FECG monitoring signals such that signals are compatible with first and second input connector 140A, 140B of monitoring device 140. The replicated monitoring signals are outputted through first and second output cable 151A, 151B, received by first and second input connector 140A 140B, respectively, of monitoring device 140 and the medical signals are presented on display 141.

In another embodiment of the present disclosure, the medical signal may be altered by signal processing circuitry 160. Alteration of the replicated signal may remove an incompatibility that exists between the signal and monitoring device 140, may increase compatibility of the signal with the monitoring device 140 or may aid a clinician in recognizing a characteristic of the signal. For example, a FECG from an electrode array 120 may need to be inverted in order for the signal to be indicative of a signal received from a second medical device and compatible with monitoring device 140. Alternatively, an offset may be added to the signal for the signal to be in a specific range (e.g. current or voltage range), or in order for a trigger or counting mechanism in the monitoring device 140 to recognize the signal. Low strength signals, or a portion of a low strength signal, may be amplified, re-scaled or otherwise altered. Alterations may be required to satisfy various criteria set by monitoring device 140 such as signal strength, signal quality, peak amplitude or signal energy.

In another embodiment of the present invention, signal replication medical apparatus 100 may replicate a signal indicative of a fault condition recognized by monitoring device 140. For example, monitoring device 140 may indicate a fault condition on display 141 when the input is either open or shorted. Signal replication medical apparatus 100 may simulate this fault condition by replicating a signal indicative of an open or shorted medical device when signal processing circuitry 160 is unable to extract a medical signal from the monitoring signals. Signal replication medical apparatus 100 may replicate any such fault signal recognized by monitoring device 140.

In another embodiment of the present disclosure, signal processing circuitry 160 performs at least one diagnostic check on electrical cable 150 as described in a U.S Utility Patent Application titled Cable Monitoring Apparatus, Attorney Docket Number H-KN-00513 (1502-143), concurrently filed on September 29, 2006 with the present application, the entire contents of which are incorporated herein by reference. Referring to FIGS. 1 and 2, signal processing circuitry 160 connects to various indicators 112 that indicate the results of a diagnostic check of electrical cable 150 attached between first input connector 110 and first diagnostic connectors 111. Diagnostic check may include testing continuity and impedance of the various conductors and connectors, testing continuity and impedance between various conductors, testing capacitive properties of the cable or conductors, testing insulation in the cable, measuring losses in the cable and conductors, measuring frequency response and signal losses at various frequencies and any other test known in the art. Various indicators 112 are indicative of at least one operating feature of the electrical cable 150 which include test performed, or measurements made, on the cable. Indicators 112 may be audible indicators, visual indicators, or any indicators known in the art, or combination thereof.

First connector 110 may interface with various medical devices including a medical electrode, a medical electrode array, an abdominal strain gage, a tocodynamometer, an intrauterine pressure catheter, an ultrasound transducer, a vacuum pressure sensor, a pulse oximeter, a pH sensor, a cervical dilation sensor, a cervical effacement sensor, a cervical length sensor and a fetal station sensor. Signal replication medical apparatus 100 may receive monitoring signals from any number of medical devices and supply replicated monitoring signals to any number of monitoring devices.

In yet another embodiment of the present disclosure first connector 110 and second connector 111 may receive medical signal from a first medical device 120 and second medical device (not shown). Signal processing circuitry 160 may select the source of the replicated signal from the first input connector 110 or from the second input connector 111. Selection may be performed automatically by the signal processing circuitry 160 or selection may be performed manually by a clinician. Signal processing circuitry 160 may use various criteria to automatically select an input, such as, for example, signal quality, signal strength and/or the functionality of the medical devices. Alternatively, clinician may select an input via the input selector switch 113.

A medical electrode and various medical uses are well know in the art. A medical electrode array is medical device containing a plurality of medical electrodes as described in U.S. Application No. 60/798,842 to Meyer, the contents of which are incorporated herein by reference. Abdominal strain gages, tocodynamometers, intrauterine pressure catheters and ultrasound transducers are also well know in the art.

Lesser known devices include a vacuum pressure sensor, a fetal pulse oximeter, a pH sensor, a cervical dilation sensor, a cervical effacement sensor, a cervical length sensor and a fetal station sensor. A vacuum pressure sensor measures the amount of vacuum applied to a fetal skull by a vacuum extractor, a device used to apply guiding pulls to a fetal scalp during delivery, and the vacuum measured by the vacuum pressure sensor is recorded by an external device. A fetal pulse oximeter measures the oxygen saturation of fetal blood during delivery. A measure of oxygen saturation, in conjunction with the fetal heart rate, can be used to detect abnormalities wherein a clinician may decide to proceed with a cesarean delivery. Similarly, fetal pH, measured with a fetal pH sensor, begins to decrease when oxygen saturation levels decrease. A cervical dilation sensor is used to measure the progress of labor by measuring and recording cervical dilation. A cervical effacement sensor measures the gradual softening or thinning of the cervix during the first stage of labor which may be used to predict the onset of delivery. Similarly, a cervical dilation sensor measures the dilation of the cervix during the first stage of labor. Finally, a fetal station sensor determines the relative positioning between the presenting part of the fetus, whether that be the head, shoulder, buttocks, or feet, and two parts of the maternal pelvis called the ischial spines.

An intrauterine pressure catheter is a common apparatus for measuring the fetal contractions of a maternal abdomen. Various pressure catheter components and systems are described in U.S. Patent No. 5,566,680 to Urion et al., the contents of which are incorporated herein by reference. When using a monitoring device 140 configured to receive a monitoring signal from an IUP catheter it often becomes necessary or desirable to "zero" or "re-zero" the monitoring device 140. U.S. Patent Application 10/952,942 to Zaiken, titled Intrauterine Pressure Catheter Interface Cable System and filed on September 29, 2004, the entire contents of which are incorporated herein by reference, describes use of a pressure catheter, a zero / re-zero apparatus and method of use.

In yet another embodiment of the present disclosure the zero / re-zero function as described in a U.S Utility Patent Application titled Cable Monitoring Apparatus, Attorney Docket Number H-KN-00512 (1502-143), concurrently filed on September 29, 2006 with the present application, may be incorporated into a signal replication medical apparatus 100. Referring to FIGS. 1 and 2, zero / re-zero circuitry 130 of the signal replication medical apparatus 100 includes a zero / re-zero selector 132 and zero / re-zero indicator 134. Clinicians initiate a zero / re-zero of the monitoring device 140 by depressing the zero / re-zero selector 132 on the signal replication medical apparatus 100. Signal replication medical apparatus 100 replicates a zero-voltage signal on the first output cable 151A for a predetermined period of time and zero / re-zero indicator 134 indicates that a zero voltage signal is being replicated. Clinicians then depress a zero / re-zero selector on the monitoring device 140 while the zero voltage signal is replicated.

In yet another embodiment of the present disclosure, indicators I may correspond to electrodes 121 on the electrode array 120 applied to the maternal abdomen A. With reference to FIG. 1, indicator circuit 170 is operably connected to the signal processing circuitry 160 and signal processing circuitry 160 may drive the indicators I with a signal indicative of at least one operating feature of electrical cable 150. An operating feature of electrical cable 150 may be associated with the functionality of the electrical cable 150, the quality of the signal transmitted by electrical cable 150, or a feature of electrical cable 150 or medical signal.

In yet another embodiment of the present disclosure, one or more of indicators I include a light driven by a signal from the signal processing circuitry 160 wherein the signal is indicative of the monitoring signal or the functionality of electrical cable 150. Indicator I may be driven with a signal proportional to the monitoring signal from the medical device, such as an electrode array 120. Clinicians can troubleshoot problems with an electrical cable 150 or medical device by observing indicator I on the signal replication medical apparatus 100.

Referring now to FIG. 3, programming flowchart 200 illustrates processes executed by the DSP 160B for performing the functions described herein in accordance with the present disclosure. While the programming flowchart of FIG. 3 includes multiple embodiments of the present disclosure, the steps executed by the DSP 160B may be limited to one or more of the various embodiment described herein.

In Step 202 an analog monitoring signal from one or more medical devices is converted from an analog format to a digital representation of the analog monitoring signal. As is known in the art, A/D conversion is not a single step but a real-time process.

In Step 204 the digital representation of the analog monitoring signal is processed. Processing may include extracting a medical signal from a monitoring signal, extracting a medical signal from a plurality of monitoring signals or determining if an extracted medical signal is a valid representation of the expected signal.

In Step 206 the format of replicated data is determined. The extracted medical signal may be replicated as a monitoring signal indicative of a signal having been outputted from a second medical device, wherein the monitoring signal from the second medical device is different that the monitoring signal converted in Step 202. The replicated data may be a zero-voltage signal, replicated for a predetermined period of time, supplied to the monitoring device 140 to perform a zero / re-zero of the monitoring device 140. The replicated data may also be indicative of a fault condition recognized by monitoring device 140.

In Step 208 the replicated data format determined in Step 206 is generated into a digital representation of a monitoring signal. Replicated data may be altered in order to remove an incompatibility between the signal and monitoring device 140, to increase compatibility of the signal with the monitoring device 140 or to aid a clinician in recognizing an element of the signal.

In Step 210 the replicated data generated in Step 208 is converted into a format recognized by the monitoring device 140. Format may be analog or digital and may be transmitted to the monitoring device 140 by a cable 151a, 151b or by any method of wireless transmission used to transmit a signal.

While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.